opengl使用FBO离屏渲染图片

1. #include

2. #include

3. #include

4. #include

5.  

6. #pragma comment(lib, "glew32.lib")

7.  

8. GLuint imageFBO;

9. GLuint imageID;

10. GLuint depthTextureID;

11. void SetFrameBufferObject(int fbowidth, int fboheight)

12. {

13. // 创建FBO对象

14. glGenFramebuffersEXT(1, &imageFBO);

15. // 启用FBO

16. glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, imageFBO);

17.  

18. // 创建纹理

19. glGenTextures(1, &imageID);

20. // 启用纹理

21. glBindTexture(GL_TEXTURE_2D, imageID);

22. glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, fbowidth, fboheight, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);

23. glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);

24. glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);

25. glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);

26. glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

27. glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, imageID, 0);

28.  

29. //

30. glGenRenderbuffersEXT(1, &depthTextureID);

31. glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, depthTextureID);

32. glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT,GL_DEPTH_COMPONENT, fbowidth, fboheight);

33. glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT,GL_DEPTH_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, depthTextureID);

34.  

35. GLenum status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);

36. if(status != GL_FRAMEBUFFER_COMPLETE_EXT)

37. printf( "FBO Initialization Failed.");

38.  

39. glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);

40. }

41.  

42. int IMAGE_WIDTH = 250;

43. int IMAGE_HEIGHT = 250;

44.  

45. void GenImage()

46. {

47. glPushMatrix();

48. glViewport(0, 0, IMAGE_WIDTH, IMAGE_HEIGHT);

49. glMatrixMode(GL_PROJECTION);

50. glLoadIdentity();

51.  

52. glMatrixMode(GL_MODELVIEW);

53.  

54. glShadeModel(GL_SMOOTH);

55. glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, imageFBO);

56. glDrawBuffer(GL_COLOR_ATTACHMENT0_EXT);

57. glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

58. glBegin(GL_POLYGON);

59. glColor3f(1.0,0.0,0.0); glVertex3f(-1.0, -1.0, 0.0);

60. glColor3f(0.0,1.0,0.0); glVertex3f(-1.0, 1.0, 0.0);

61. glColor3f(0.0,0.0,1.0); glVertex3f(1.0, 1.0, 0.0);

62. glColor3f(1.0,0.0,0.0); glVertex3f(1.0, -1.0, 0.0);

63. glEnd();

64.  

65. glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);

66. glPopMatrix();

67. }

68.  

69. static GLuint texName;

70.  

71. void display(void)

72. {

73. // 离屏渲染纹理

74. GenImage();

75.  

76. glViewport(0,0,250,250);

77. glClear(GL_COLOR_BUFFER_BIT);

78. glEnable(GL_TEXTURE_2D);

79. glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);

80. //切换屏幕

81. glBindFramebufferEXT(GL_FRAMEBUFFER_EXT,0);

82. // 启用离屏渲染的纹理影像

83. glBindTexture(GL_TEXTURE_2D,imageID);

84. // 创建Mipmap(多重细节层)

85. glGenerateMipmapEXT(GL_TEXTURE_2D);

86.  

87. // 绘制纹理影像

88. glBegin(GL_QUADS);

89. glTexCoord2f(1.0, 0.0); glVertex3f(-1.0, -1.0, 0.0);

90. glTexCoord2f(0.0, 1.0); glVertex3f(-1.0, 1.0, 0.0);

91. glTexCoord2f(1.0, 1.0); glVertex3f(1.0, 1.0, 0.0);

92. glTexCoord2f(1.0, 0.0); glVertex3f(1.0, -1.0, 0.0);

93. glEnd();

94.  

95. glutSwapBuffers();

96. glDisable(GL_TEXTURE_2D);

97. }

98.  

99. void reshape(int w, int h)

100. {

101. glViewport(0, 0, (GLsizei) w, (GLsizei) h);

102. glMatrixMode(GL_PROJECTION);

103. glLoadIdentity();

104. }

105.  

106. void keyboard (unsigned char key, int x, int y)

107. {

108. switch (key) {

109. case 27:

110. exit(0);

111. break;

112. default:

113. break;

114. }

115. }

116.  

117. int main(int argc, char** argv)

118. {

119. glutInit(&argc, argv);

120. glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);

121. glutInitWindowSize(250, 250);

122. glutInitWindowPosition(100, 100);

123. glutCreateWindow(argv[0]);

124. glewInit();

125. glutDisplayFunc(display);

126. glutReshapeFunc(reshape);

127. glutKeyboardFunc(keyboard);

128. // 设置创建虚拟屏幕

129. SetFrameBufferObject(IMAGE_WIDTH, IMAGE_HEIGHT);

130.  

131. glutMainLoop();

132. return 0;

133. }

134.